This invention relates generally to sampling means and methods and relates, more particularly, to the means and methods for obtaining samples from areas, or spots, on a surface to be analyzed.
The sampling collection techniques with which this invention is concerned involve the positioning of a collection instrument or other sample collection device in relatively close proximity to a surface to be analyzed, or sampled, for purposes of gathering an amount (e.g. ions) of the surface for analysis. An example of one such collection technique is used in conjunction with desorption electrospray ionization (DESI) mass spectrometry, but other techniques, such as may involve desorption atmospheric pressure chemical ionization (DAPCI) or matrix-assisted laser desorption/ionization (MALDI), are applicable here as well. In any of such techniques, it is desirable that the collection instrument be maintained at a predetermined, or desired, distance from the surface to be sampled for optimum collection results and to reduce the likelihood that the collection results will be misinterpreted when subsequently analyzed.
Furthermore, there exists some sample-collecting processes which involves a self-aspirating emitter through which an agent is delivered to the surface during the sample-collection process in a spray plume. Such an emitter is commonly fixed in position relative to the sample collection instrument, or device, so that the spray plume is directed toward the surface at a predetermined, or fixed, angle of incidence so that the delivered spray plume is intended to strike the surface to be sampled at a predetermined location for effecting the movement of an amount of the surface to be sampled toward the collection instrument. In other words, there is a desirable spatial assignment which exists between the emitter, the collection instrument and the surface to be analyzed so that if the surface is not accurately positioned in a location (e.g. within a predetermined plane) in which the surface is intended to be positioned, poor collection results are likely to be obtained.
To obviate the need for an operator to make manual adjustments to the distance between the sample collection instrument and the surface during the course of a sample collection process, it would be desirable to provide a system and method for accurately controlling the sample collection device-to-surface distance during a sample collection process.
Accordingly, it is an object of the present invention to provide a system and method for automatically controlling the distance between a sample collection instrument, or device, and the surface to be analyzed, or sampled, with the instrument which utilizes a laser sensor for monitoring the actual collection instrument-to-surface distance during the sampling procedure.
Another object of the present invention is to provide such a system and method wherein the collection instrument-to-surface distance is continually monitored throughout the sampling procedure and adjusted, as necessary, so that the collection instrument-to-surface distance is maintained at an optimal spacing.
Yet another object of the present invention is to provide such a system which reduces the likelihood that the results of the sample collection process will be misinterpreted when analyzed.
A further object of the present invention is to provide such a system which, when used in conjunction with sample-collecting operations which utilize an emitter which is directed at a predetermined angle toward the sample helps to maintain the proper spatial assignment between the emitter, the collection instrument and the surface to be analyzed during a sample collecting process.
Yet another object of the present invention is to provide such a system which is uncomplicated in structure, yet effective in operation.